Liquid crystal display devices ranging from a large display device such as a television receiver to a small display device such as a mobile phone have been spreading. Products with higher added values will be needed from now on and are being developed. In recent years, in view of rising interest in the global environment and improvement of the convenience of mobile devices, development of liquid crystal display devices with low power consumption has attracted attention.
Non-Patent Document 1 discloses a structure of a liquid crystal display device where refresh rates differ between the case of moving image display and the case of still image display for reduction in power consumption of the liquid crystal display device. Non-Patent Document 1 also discloses a structure where AC signals with the same phase are supplied to a signal line and a common electrode also in an idle period so that fluctuation in drain-common voltage can be prevented, in order that perception of flickers due to the fluctuation in drain-common voltage may be prevented, which is caused by switch of signals between the idle period and a scan period in the case of still image display.